U.S. patent application number 10/657831 was filed with the patent office on 2004-05-13 for vibration resistive steering wheel and method.
Invention is credited to Bostick, William E., Cox, William B. JR., Halifax, Michael A., Lowrie, Anderson G..
Application Number | 20040089096 10/657831 |
Document ID | / |
Family ID | 32233034 |
Filed Date | 2004-05-13 |
United States Patent
Application |
20040089096 |
Kind Code |
A1 |
Bostick, William E. ; et
al. |
May 13, 2004 |
Vibration resistive steering wheel and method
Abstract
A steering wheel (310) for a motor vehicle includes a core
member with a circular rim (312). At least one dampening element
(314) is attached to the rim (312) and is supported and sprung in a
sleeve (318) by at least one spring element (316). A method of
manufacturing a steering wheel (310) is also provided, the method
including steps of providing a steering wheel core member (312),
and securing a sleeve (318) having at least one dampening element
(314) supported and sprung therein to the core member (312). A
method of optimizing vibration in a vehicle steering wheel assembly
is further provided.
Inventors: |
Bostick, William E.; (St.
Clair, MI) ; Cox, William B. JR.; (Berkley, MI)
; Halifax, Michael A.; (Fort Gratiot, MI) ;
Lowrie, Anderson G.; (Port Huron, MI) |
Correspondence
Address: |
Laurence C. Begin
Dinnin & Dunn, P.C.
Suite 500
2701 Cambridge Court
Auburn Hills
MI
48326
US
|
Family ID: |
32233034 |
Appl. No.: |
10/657831 |
Filed: |
September 9, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10657831 |
Sep 9, 2003 |
|
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|
10223137 |
Aug 19, 2002 |
|
|
|
60409290 |
Sep 9, 2002 |
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Current U.S.
Class: |
74/552 |
Current CPC
Class: |
B62D 7/222 20130101;
F16F 7/104 20130101; B62D 1/06 20130101; Y10T 74/20834
20150115 |
Class at
Publication: |
074/552 |
International
Class: |
B62D 001/04 |
Claims
What is claimed:
1. A steering wheel for a motor vehicle comprising: a core member
having a substantially circular rim; at least one dampening element
secured about or within said rim in vibrational communication
therewith, said dampening element comprising a periphery; at least
one spring member extending about said periphery thereby supporting
said dampening element; and a sleeve positioned about said
dampening element, thereby covering the dampening element within
said steering wheel.
2. The steering wheel of claim 1 further comprising a plurality of
spring members symmetrically oriented about said dampening
element.
3. The steering wheel of claim 2 wherein said spring member is an
O-ring.
4. The steering wheel of claim 2 wherein said plurality of spring
members is a plurality of O-rings.
5. The steering wheel of claim 1 wherein said dampening element has
a density greater than the density of said core member.
6. The steering wheel of claim 1 wherein said spring member is
formed from a resilient material or polymer.
7. The steering wheel of claim 1 wherein the substantially circular
rim comprises a channel substantially complementary with said
dampening element.
8. A method of manufacturing a steering wheel comprising the steps
of: providing a steering wheel core member having a circular rim;
providing at least one dampening element having a periphery;
positioning at least one spring member about the periphery of the
dampening element; positioning the at least one dampening element
in a sleeve, the spring member resiliently supporting the dampening
element therein; and securing the sleeve about or within the rim of
the steering wheel core member, thereby providing resilient
suspension of the dampening element relative to the steering wheel
core member.
9. The method of claim 8 further comprising the steps of:
positioning the core member and sleeve in a molding apparatus; and
delivering a flowable curable material into the molding apparatus,
wherein the cured material adheres to the sleeve and core member,
and is insulated from the dampening element and at least one spring
member by the sleeve.
10. The method of claim 8 wherein the at least one dampening
element comprises a plurality of dampening elements secured in at
least one sleeve about the rim of the core member.
11. The method of claim 8 wherein the at least one spring member
comprises a plurality of spring members.
12. The method of claim 10 wherein the at least one spring member
comprises a plurality of spring members.
13. The method of claim 12 wherein the at least one spring member
comprises a plurality of O-rings.
14. The method of claim 8 wherein the steering wheel rim comprises
a channel for receipt of the sleeve.
15. A steering wheel formed according to the method of claim 8.
16. A method of providing for optimal vibration in a vehicle
steering wheel assembly comprising the steps of: forming a steering
wheel core member having a substantially circular rim portion, the
core member being connectable to a vehicle steering system;
providing at least one dampening element having a periphery;
positioning at least one spring element about the periphery of the
at least one dampening element to form at least one spring
assembly; positioning the at least one spring assembly in a sleeve,
wherein the at least one dampening element is resiliently supported
in the sleeve by the at least one spring element; rotationally
fixing the sleeve about the rim portion; wherein resilient support
by the at least one spring element of the at least one dampening
element facilitates resilient relative displacement between the
sleeve and dampening element during vibration of the steering wheel
assembly, thereby attenuating vibrations imparted thereto from the
vehicle steering system.
17. The method of claim 16 wherein the at least one dampening
element is formed from a material having a density greater than a
density of the core member, thereby imparting an increased inertial
resistance to vibration of the steering wheel assembly.
18. The method of claim 16 further comprising the steps of:
providing a plurality of sleeves, each having a dampening element
with a different mass resiliently supported therein; measuring
vibration of the steering wheel assembly with each of the selected
sleeves secured to the steering wheel core; and selecting a sleeve
from the plurality of sleeves to impart optimal vibration
resistance to the steering wheel assembly based on vibrational
characteristics imparted to the steering wheel assembly when
secured thereto.
19. The method of claim 16 further comprising the steps of:
positioning a first number of resilient spring elements about a
periphery of a dampening element; placing the dampening element
with the first number of resilient spring elements in a sleeve, and
securing the sleeve to a steering wheel core; measuring vibration
of the steering wheel core with the sleeve mounted thereon;
positioning a second number of resilient spring elements about a
periphery of a dampening element; placing the dampening element
with the second number of resilient spring elements in a sleeve,
and securing the sleeve to a steering wheel core; measuring
vibration of the steering wheel core with the sleeve mounted
thereon; and selecting a number of spring elements for positioning
on the dampening element to impart optimal vibration resistance to
the steering wheel assembly based on vibrational characteristics
imparted to the steering wheel assembly when secured thereto.
20. The method of claim 16 further comprising the steps of:
positioning a first at least one spring element having a first
width about a periphery of a first dampening element; placing the
first dampening element with the first spring element having the
first width in a sleeve, and securing the sleeve to a steering
wheel core; measuring vibration of the steering wheel core with the
sleeve mounted thereon; positioning a second at least one spring
element having a second width different from the first width about
a periphery of a second at least one dampening element, said first
at least one dampening element equivalent to said second at least
one dampening element; placing the second at least one dampening
element with the second at least one spring element having a second
width in a sleeve, and securing the sleeve to a steering wheel
core; measuring vibration of the steering wheel core with the
sleeve mounted thereon; and selecting a width of spring elements
for positioning on the dampening element to impart optimal
vibration resistance to the steering wheel assembly based on
vibrational characteristics imparted to the steering wheel assembly
when secured thereto.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of the filing date of
Provisional Application No. 60/409,290, filed on Sep. 9, 2002. This
application is also a continuation-in-part of co-pending U.S.
application Ser. No. 10/223,137 having a filing date of Aug. 19,
2002.
TECHNICAL FIELD
[0002] The present invention relates generally to steering wheels
and vehicle steering assemblies, and more particularly to a
steering wheel or steering assembly having increased resistivity to
vehicle and rotational vibration.
BACKGROUND OF THE INVENTION
[0003] A longtime goal of automotive designers has been minimizing
vibration in various vehicle systems during operation. Reductions
in vibration can offer the advantages of less wear and tear on
vehicle parts and higher operating efficiency due to less energy
wasted by vibrating components, as well as greater comfort for the
operator. Because structural and functional details of automobiles
differ greatly among different vehicle lines and models, vibration
suppression criteria for one vehicle may differ from that of other
vehicles. Moreover, vibrational characteristics change when new
system or structural technologies, and even new styling designs are
incorporated into existing vehicle models.
[0004] Of particular interest to designers has been the development
of vibration dampeners in vehicle steering wheels. Lessening
vibrations communicated through the steering system can reduce
operator fatigue and vehicle noise, and enhance overall driving
enjoyment. Some methods of reducing vibration in the steering
system have focused on the use of damper weights to absorb
vibrations communicated through the steering column, and various
methods are known in the art. In one approach, resilient members
are used to join an airbag module to the steering wheel, thereby
allowing the airbag module to act as a mass damper. In this
approach, however, such systems require a relatively heavy airbag
module to effectively suppress rotational vibrations. Other systems
utilize a mass damper directly associated with the steering column.
Again, such systems are relatively complex and require a relatively
large mass.
SUMMARY OF THE INVENTION
[0005] In one aspect, a steering wheel for a motor vehicle is
provided preferably having a dampening element positioned in a
sleeve and secured about a steering wheel core. At least one spring
member preferably extends about a periphery of the dampening
element and resiliently supports the dampening element in the
sleeve. More preferably, a plurality of spring members is provided,
and symmetrically positioned about the dampening element. The
sleeve preferably insulates the dampening element and spring member
assembly during the foam mold steering wheel manufacturing process,
thereby resulting in a suspended sprung mass or dampener within the
steering wheel interior.
[0006] In another aspect, a method of optimizing vibration in a
vehicle steering wheel assembly is provided. The method preferably
includes the steps of forming a steering wheel core member having a
substantially circular rim portion, the core member being
connectable to a vehicle steering system, and positioning at least
one dampening element in a sleeve, wherein the dampening element is
resiliently supported in the sleeve by at least one spring element.
The method further preferably includes the step of securing the
sleeve about the rim portion and rotationally fixing the sleeve
relative thereto. Resilient support of the dampening element by the
spring element(s) facilitates resilient and relative displacement
between the sleeve and dampening element during vibration of the
steering wheel assembly, thereby attenuating vibrations imparted
thereto from the vehicle steering system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a partial cross-sectional view of a steering wheel
according to a first constructed embodiment of the present
invention.
[0008] FIG. 2 is a partial elevational view of a steering wheel
according to a constructed embodiment of the present invention
similar to FIG. 1.
[0009] FIG. 3 is a partial cross-sectional view of a steering wheel
according to a second constructed embodiment of the present
invention.
[0010] FIG. 4 is a partial cross-sectional view of a steering wheel
according to a third constructed embodiment of the present
invention.
[0011] FIG. 5 is a partial cross-sectional view of a steering wheel
according to a fourth constructed embodiment of the present
invention.
DETAILED DESCRIPTION
[0012] Referring to FIGS. 1 and 2, there are shown partial views of
a steering wheel 10 according to a preferred embodiment of the
present invention. Steering wheel 10 has a core 12 with a
substantially circular rim 13. The core 12 is preferably die cast
or machined from metal. A channel 11 is preferably formed within
the rim 13 for placement of a dampening element as explained below.
A dampening element 14 is secured about or within rim 13 and is
preferably positioned at least partially within channel 11, and
secured therein. In a preferred embodiment, the steering wheel core
is die cast aluminum or magnesium, and is formed as a unitary core
member having a plurality of spokes (not shown) connecting core 12
to a central body (not shown), and mounted to a vehicle steering
system in a conventional manner. When fully assembled, steering
wheel 10 is preferably covered with a known covering material, for
example plastic, leather, or fabric. Securing dampening element 14,
preferably formed of a relatively dense material, to rim 13
increases the moment of inertia of the steering wheel as well as
the rotational mass moment of inertia, increasing its resistance to
rotational vibration. It should be appreciated that actually
providing a channel 11 in rim 13 is not critical for purposes of
the present invention, however, a channel helps in positioning and
retaining the dampener weight, and thus represents a preferred
embodiment. Those skilled in the art will appreciate that securing
dampener 14 "about" rim 13 encompasses a wide variety of securing
means, and it is not necessary that dampener 14 be actually
attached to rim 13 itself.
[0013] Channel 11 is preferably substantially U-shaped in
cross-section, but might vary considerably without departing from
the scope of the present invention. In a preferred embodiment,
channel 11 is molded when casting the unitary core member; however,
the channel might instead be machined. Alternatively, the entire
rim 13 might be manufactured as a separate piece, and attached to
spokes and a central mount portion to assemble the core member 12.
Rather than a U-shaped channel, rim 13 might have, for example, a
T-shaped, square, semi-circular, or V-shaped channel. FIG. 3
illustrates a T-shaped channel 111 mounted in a steering wheel 110.
Returning to FIGS. 1 and 2, dampener 14 can similarly be formed
having a variety of cross-sectional geometries, preferably designed
to substantially match the cross section of channel 11, wherein
dampener 14 is positioned. In a preferred embodiment, channel 11 is
continuous around circular rim 13; however, it should be
appreciated that rim 13 might have a plurality of channels,
separated by filled-in regions, positioned circumferentially around
rim 13. One preferred die casting process leaves portions of the
channel filled wherein the die is gated for molten metal delivery.
Dampener 14 is preferably a complete or partial ring made from a
material denser than core 12, for instance lead, steel, tungsten,
or some other metal. The dampening element(s) 14 may also be a
sufficiently dense non-metallic material, for example, a dense
polyvinyl chloride (PVC). Various designs are possible, and rather
than a ring or partial ring, dampener 14 might instead comprise a
plurality of pieces preferably positioned substantially
symmetrically around steering wheel 10. Although the dampening
element is preferably substantially radially symmetrical about the
rim, alternative constructions are contemplated in which the mass
may be asymmetrically oriented about the center of the wheel. In
yet another embodiment, two partial circle members are utilized
rather than a continuous ring. In this embodiment, the two distinct
members can be positioned in channel 11, allowing the discontinuous
dampener structure 14 to accommodate the solid regions resulting
from the molding process and the gates in the die. In the present
description, dampener 14 is referred to in the singular, however,
it should be appreciated that the descriptions herein are equally
applicable to embodiments employing multiple dampeners 14. In still
other contemplated embodiments, as illustrated in FIG. 4, a channel
211 is filled with a metallic powder or metal grindings/turnings
214 that can be pressed in the channel 211 to retain the material
therein or, alternatively, heated and pressed to form dampening
members that can be manipulated similar to dampener members/rings,
as described above.
[0014] Returning to FIGS. 1-4, a variety of different methods of
mounting dampener 14 about rim 13 is contemplated. In a preferred
embodiment, dampener 14 is mounted substantially within channel 11;
however, it might be mounted wholly or only partially within
channel 11 depending on the dimensions of the dampener 14 and the
channel 11 itself. Thus, as used herein, the term "within" will be
understood to mean fully, as well as partially in the channel 11.
Moreover, as described above, the use of a channel is not critical,
and a weighted dampener member might be secured to the steering
wheel rim 13 by other means. For example, rather than a channel 11
in the rim 13, the rim 13 itself might be formed with a rounded
outer surface matable with a channel in the dampener 14. Further, a
channel type of interface is not necessary at all. The dampening
element 14 might, for instance, be formed with a flattened side
that could be positioned flush with a flattened portion of the rim
13. The dampening element 14 could be attached to the rim 13 with
fasteners, adhesive, or even spot welded. Various additional
alternatives are possible, and those skilled in the art will
appreciate that a great variety of different shaped rims and
dampeners might be used without departing from the scope of the
present invention. "Vibrational communication," as used herein,
will be understood to mean that vibrations are communicated between
two or more structures.
[0015] In a preferred mounting method, the rim 13 (and core member
12) with the associated or inserted dampener 14 are positioned in
an injection mold (not shown) with channel 11 facing upward. Next,
a multiple-component elastomeric foaming material is delivered to
the mold, in a process known in the art as reaction injection
molding. The foam material, or adherent, is preferably a
polyurethane foam or composite as known in the art, and adheres to
dampener 14 and to rim 13, holding dampener 14 in its desired
position and providing a resilient coating layer on the exterior of
the wheel. Stated another way, the foam mold process may be used to
"rotationally fix" the rim 13 to the dampener element 14. The
article may subsequently be painted, or covered with leather,
plastic, etc. to finish the steering wheel. It should further be
appreciated that dampener 14 is preferably formed from a material
having a melting point sufficient to withstand the temperature
during reaction injection molding, which generally ranges from
100.degree. C. and above, and more specifically from 100.degree. C.
to 120.degree. C. An illustrative example of a suitable injection
molding method is described in U.S. Pat. No. 6,386,063 to Hayashi
et al., herein incorporated by reference. Those skilled in the art
will appreciate that a wide variety of known adhesives and
elastomeric materials could be used as the steering wheel
covering/dampener-retaining material without departing from the
scope of the present invention.
[0016] Dampener 14 is thus secured in the channel 11 by the foam,
however, the preferably flexible, resilient nature of the foam can
impart a degree of freedom of movement to dampener 14. Dampener 14
can be mounted in channel 11 such that the dampener piece(s) are in
continuous contact with the rim 13, allowing translational and
rotational vibrations from the core to be transmitted directly to
the dampener.
[0017] Alternatively, a layer of foam or other resilient material
might be disposed between the dampener and the core, allowing the
foam to absorb energy before transmitting the energy to the
dampener. Such a design allows some of the energy of rotational
vibration to be absorbed by expansion and contraction of the foam.
Likewise, the use of resilient foam also increases resistance to
translational vibration, expansion and contraction of the foam
allowing the dampener to suppress non-rotational, i.e. linear
vibrations. Other methods of affixing (or "rotationally fixing")
dampener 14 to the core member are contemplated, including
mechanical attachment(s), such as rivets or screws, or tabs
attached to rim 13 that can be bent over to secure dampener 14 in
place. In an embodiment utilizing tabs to hold dampener 14 in
place, the tabs may be formed integrally with rim 13 in a die
casting process, or they may be attached separately after forming
rim 13. Still other contemplated methods of affixing dampener 14 to
rim 13 include press-fitting dampener 14 into channel 11, or
crimping rim 13 to secure dampener 14 therein or thereabout.
[0018] It is believed that adding weight around the rim of steering
wheel 10 increases the polar mass moment of inertia of the wheel,
increasing resistance to rotational vibration in the steering
wheel. When mass is added at the exterior of the wheel, the
rotational inertia of the wheel increases more than when an equal
mass is added closer to the axis of rotation of the wheel (center
body). The value of rotational inertia for a hoop rotated about a
cylinder axis, similar to the rim of a steering wheel rotated about
the steering column, can be expressed by the equation:
I=MR.sup.2
[0019] "I" is the rotational inertia, "M" is the mass of the rim
(hoop), and "R" is the radius of the hoop. Although this expression
only approximates the result of attaching the instant dampener 14
to the steering wheel, those skilled in the art will appreciate
that rotational inertia generally increases with the square of the
distance between the point where the mass is added and the axis of
rotation. In many steering wheel designs, the actual axis of
rotation is not at the exact center of the wheel, however, this
mathematical relationship is generally applicable. Therefore, with
greater rotational inertia, i.e. greater force required to initiate
or reverse rotation of the steering wheel, the wheel has an
increased resistance to rotational vibration. Because mass is added
only where it has the most efficacious dampening effect, at the
rim, the total mass that must be added to reduce vibration is
minimized. By minimizing the required mass, the natural frequency
of vibration of the steering wheel is not lowered as much as in
systems that, for example, utilize a relatively larger mass, added
closer to the center of the wheel. It has been a goal of designers
to avoid constructing steering wheel systems with a natural
vibration frequency close to natural frequencies encountered in
operation of the vehicle as a whole, for instance that of the
engine or the vehicle itself. As presently understood, the present
invention allows a minimal amount of mass to be added, maintaining
the natural frequency of vibration of the steering wheel at a value
different from the vehicle or engine natural vibration frequencies,
thereby minimizing undesirable resonance vibration of the steering
wheel. Furthermore, avoiding the need to add an excessive amount of
mass is less expensive and reduces the risk of significantly
altering the crash performance of the steering system and related
components, a problem that can arise where relatively large masses
are added to the airbag module, or elsewhere close to the wheel's
axis of rotation.
[0020] A problem related to rotational vibration involves the
phenomenon known in the art as "lumpy return." When a vehicle is
directed into a turn, the steering wheel's subsequent return to its
center position may take place through a series of jerky or bumpy
motions rather than the desired smooth action. Adding mass to the
wheel, particularly the addition of mass at the exterior, reduces
the degree to which variations in the road surface, as well as
fluctuations in the power steering operation, can reduce the
smoothness of the wheel's return to its center position. Likewise,
adding mass to the steering wheel increases the resistance of the
wheel to translational, i.e. non-rotational vibrations.
[0021] In a related aspect, the present invention provides a
tunable method of optimizing, e.g. increasing resistivity to,
rotational vibration in a vehicle steering wheel. In different
vehicle lines, and even in vehicles of the same make and model,
subtle differences in components and production may cause optimal
rotational vibration characteristics to vary. In a preferred
embodiment, dampeners having various densities, sizes,
configurations, and weights are made available for attachment to
steering wheel 10. Simulation apparatuses, well known in the art,
are used to simulate, for example, smooth road, bumpy road, and
turning conditions encountered by a vehicle steering system. Thus,
objective measurements of vibration amplitude and frequency can be
recorded under varying simulated conditions. During testing,
different rings or alternative dampening structures are inserted
into the channel 11, giving the steering system greater or lesser
resistance to rotational vibration, and greater or lesser natural
vibration frequencies. In this fashion, the individual ring(s) or
dampeners imparting vibration characteristics appropriate to a
particular vehicle may be selected. A preferred testing sequence
involves assembling a steering wheel apparatus without a dampening
insert 14, then mounting the steering apparatus on the simulator to
determine the vibration characteristics under different conditions.
The next step, if necessary, involves mounting the heaviest of a
plurality of available dampeners into the channel 11, then
performing a second series of tests to determine the vibration
characteristics with the weighted steering wheel. If satisfactory,
the "heavy" dampener will be used for that vehicle, or line of
vehicles. If unsatisfactory, the various other dampeners will be
tested with the steering apparatus until the optimum dampener(s)
is/are determined. A test rig for assessing rotational vibration
characteristics of a steering wheel, and a method of doing so is
described in Giacomin, J., Shayaa, M. S., Dormegnie, E. and
Richard, L. 2001, A Frequency Weighting Curve For The Evaluation Of
Steering Wheel Rotational Vibration, Submitted to the Journal of
Sound and Vibration, and viewable on the internet at
www.shef.ac.uk/mecheng/dynam/ra/human.htm. Other methods of
determining the appropriate dampeners to insert into a particular
steering wheel are contemplated, such as actual vehicle operation
tests, and subjective data obtained from test drivers. For example,
rather than the use of a simulation apparatus, drivers might
operate a vehicle under different conditions and at different
speeds, allowing experimenters to select the optimum dampener based
on the stated preferences and experience of the test drivers. In
some instances, the steering system may be fully assembled into the
vehicle, with the exception of the dampener 14. Driving tests can
be undertaken with various weighted rings and dampener designs held
in the steering wheel, and a dampener permanently molded in place
only after the optimum dampener is selected.
[0022] In yet another embodiment, a steering wheel 310 as shown in
FIG. 5 includes at least one spring member 316 and preferably a
plurality of spring members 316 positioned about the periphery of a
dampener 314, thereby effectively springing the mass or the
dampener 314. As in the other embodiments, the dampener 314 may be
a full ring housed within a channel 311 of the steering wheel core
or rim 312. In this embodiment, the mass 314 is preferably but not
necessarily, formed from a material denser than the steering wheel
core 312 wherein the mass 314 might be formed from lead, zinc, or
tungsten, for example, and the core might then be formed from
carbon steel or steel. Alternatively, the mass 314 might be two
half circles positioned in opposite halves of the steering wheel
310. Or, the mass 314 might comprise a plurality of segments
oriented symmetrically about the core 312 and within the core
channel 311. At least one spring member 316 is positioned about the
periphery of the mass 314, in intimate contact therewith. In a
preferred embodiment, a plurality of "O"-rings or polymeric spring
members 316 is snugly and symmetrically oriented about the mass 314
periphery. A sleeve 318, is preferably formed from a rigid material
or polymer such as polyvinylchloride and encapsulates or insulates
the mass and spring assembly 320 during the steering wheel foam
mold process. An inner wall 322 of the sleeve 318 additionally
provides a torsional surface wherein an outer surface(s) 324 of the
spring member(s) 316 interfaces therewith and thus exerts a torque
on the spring member 316 as vibrations occur during vehicle
operation. The dampener 314 may be rotationally fixed to the rim
313 or core 312 as described relative to other embodiments, by foam
mold for example.
[0023] Accordingly, the mass 314 is supported by the spring members
316 and therefore suspended within the sleeve 318 about the
periphery of the steering wheel 310. Resonance frequency is
therefore attenuated along a three-dimensional profile and
torsional vibration is attenuated as well.
[0024] As with the other embodiments, the fourth embodiment shown
in FIG. 5 may be tuned to accommodate various vibrational patterns
particular to a given vehicle. As presently understood, determining
the optimum amount of spring members 316 employed about the mass
314 is best accomplished through an iterative method. Stated
another way, the resonant and torsional vibrations are best
attenuated by simply employing one spring member 316 about the
dampener or mass 314, securing the steering wheel 310 within a
known testing apparatus (those used by Ford or General Motors for
example), and then determining the resonant and torsional
vibrations attendant therewith. Accordingly, the vibrations
inherent within any steering wheel assembly 320 may be inhibited or
optimized by simply adding additional spring members 316 and then
repeating the test until the vibrational frequencies fall within
customer specifications. In conjunction with varying the number of
spring elements 316, the vibrations may also be attenuated by
varying the materials used for the spring and thus varying its
inherent spring-like properties, and/or by varying the materials
used in the dampener 314, for example.
[0025] Further still, the spring elements 316 may be varied in size
to attain the desired vibrational characteristics in the steering
wheel. For example, relatively larger O-rings may deform more
against the interior walls of sleeve 318 than relatively smaller
O-rings, and will accordingly "spring" the dampener 314 differently
than the smaller O-rings. Stated another way, the relative
displacement the O-rings allow between dampener 314 and sleeve 318
while undergoing a given vibration may vary depending upon the
width of the selected O-rings, as well as other characteristics
thereof such as hardness.
[0026] As with foregoing described embodiments, the density and/or
number of dampening elements can be varied in the sprung mass
design. Thus, dampeners having relatively greater or lesser
densities can be incorporated into sleeves in accordance with the
present invention, then the different mass sleeves can be mounted
onto a steering wheel core, and vibrational characteristics
tested.
[0027] The O-rings are preferably made of a resilient polymer such
as urethane or polyurethane and may be provided from well known
sources such as Freudenberg NOK or Dupont. The sleeve 318 is
preferably made from PVC, for example, or some other rigid material
that like the material of the "O-rings" or spring members 316, can
withstand the temperatures attendant to the foam mold steering
wheel manufacturing process.
[0028] The present description is for illustrative purposes only,
and should not be construed to limit the breadth of the present
invention in any way. Thus, those skilled in the art will
appreciate that various modifications might be made to the
presently disclosed embodiments without departing from the scope of
the invention, as defined above and in terms of the claims set
forth below.
* * * * *
References